645720601 has 2 divisors, whose sum is σ = 645720602. Its totient is φ = 645720600.

The previous prime is 645720587. The next prime is 645720613. The reversal of 645720601 is 106027546.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 641102400 + 4618201 = 25320^2 + 2149^2 .

It is a cyclic number.

It is not a de Polignac number, because 645720601 - 2¹⁹ = 645196313 is a prime.

It is not a weakly prime, because it can be changed into another prime (645720671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322860300 + 322860301.

It is an arithmetic number, because the mean of its divisors is an integer number (322860301).

Almost surely, 2^645720601 is an apocalyptic number.

It is an amenable number.

645720601 is a deficient number, since it is larger than the sum of its proper divisors (1).

645720601 is an equidigital number, since it uses as much as digits as its factorization.

645720601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 645720601 is about 25411.0330565288. The cubic root of 645720601 is about 864.3339013116. Note that the first 3 decimals are identical.

The spelling of 645720601 in words is "six hundred forty-five million, seven hundred twenty thousand, six hundred one".